A pilot of a contemporary aircraft wears a helmet for his protection. Such a helmet is usually provided with at least one visor and in many cases with two visors. A typical prior art helmet, which employs two visors, is shown in U.S. Pat. No. 3,593,338. This general form of construction includes mechanisms which permit the visors to be moved between their fully raised and completely down positions. One of the mechanisms is disposed upon the right-hand side of the helmet and the other mechanism is disposed upon the left-hand side of the helmet. However, it has been found that this form of construction is somewhat disadvantageous because the control of an aircraft is nearly always done with the right hand. Thus, the pilot cannot have complete control of his aircraft if he has to switch hands to change visor position. Therefore, when dual visors are to be utilized with a helmet, it is desirable that the visor operating mechanisms be so disposed that both mechanisms can be operated by the left hand.
A construction which permits left-hand operation of dual visors is shown in West German Offenlegungsschrift 2736121. A principal disadvantage of this form of design is that the operating mechanisms extend substantially to one side of the helmet thus increasing its side profile. It is desirable that the visor operating mechanism have a generally low profile, or more specifically, be located as close to the helmet surface as possible. In addition, this device does not lock the visors to their desired positions. It is imperative to have visors that lock in position to reduce the risk of injury to the eyes should pilot ejection occur. Should a visor cease being a shield for the eyes during ejection, the force of winds encountered can cause damage if not permanent blindness to the pilot. It is a well established fact that wind blast will cause a visor(s) to lift from its lowered protective position.
Another relevant patent is U.S. Pat. No. 4,199,823. This patent discloses a dual visor helmet having actuating handles on the left-hand side. This patented design also does not provide for positive detenting positions. In addition, it is difficult to mount a visor shield in this patented design due to the actuating mechanism being disposed between the visor and its pivot. If further requires more parts which, in most cases, increases the overall weight. Due to what appears to be a substantial increase in helmet profile, this allows the possibility of parachute shroud lines to become entangled around the mechanism's handles.